I replaced the ignition switch on the Maxima but in the process all interior lights went out and now the car will not start. When connecting the diagnostic machine it is not getting any power to perform a diagnostic check. The battery has power, the head lamps and rear lamps work but there is no electrical current to any other part of the car.

 

Did you disconnect the battery prior to replacing the ignition switch?

Did you replace the switch (where key is inserted) or the wiring harness that plugs into the rear of the switch? It's traditionally the wiring harness that needs replacement...the portion that turns to make the electrical connection gets worn.

Don't forget to check the condition of your battery (ie. is it fully charged).

 

you probably blew one of the fuses that are under the hood next to the battery.

Check the FL30A IGN SW fuse, the FL75A BATTERY IGN fuse and the 7.5A BCM fuse. Feel free to check them all while you are in there.